CORROSION AND MICROFOULING OF COPPER AND ITS ALLOYS IN A TROPICAL MARINE WATERS OF INDIA (MANGALORE)

Rate of corrosion, extent and nature of microfouling of copper, cupron ickel 70/30 and cupronickel 90/10 have been studied for three differen t seasons at a station on the west coast of India. The corrosion rates for all the three materials are higher during premonsoon as compared to other two seasons. Decreasing trend in the corrosion rate has been observed with increased nickel content. The microfouling assemblage wh ich is estimated in terms of diatoms and bacterial count and their exo polysaccharide exhibited inverse relationship with corrosion rate. Mar ked seasonal variations in the extent of corrosion and microfouling ar e evident. The resistivity of copper and its alloys towards microfouli ng has been found to be in the order as Cu > Cu-Ni 90/10 > Cu-Ni 70/30 . X-ray diffraction analysis of the corrosion products revealed the pr esence of Cu2O as major component in both the alloys.